1. Field of the Invention
The present invention relates to the intimate contacting or admixture of a plurality of distinct physical phases, and plural phase contactor therefor; more especially, the invention relates to the intimate contacting of plural, distinct physical phases and ultimate separation of the various products resulting from such admixture.
2. Description of the Prior Art
A great variety of gas/liquid, and other phase contactors, mixers or separators, whether of pneumatic, mechanical, or other type, are of course well known to the state of this art. Equally well known, on the other hand, is the art appreciation of the various difficulties that are encountered in attempting to disperse, disintegrate, comminute or pulverize, e.g., a liquid in a gaseous environment or treatment phase, such as, for example, effecting the drying of certain liquid materials through a spray drying technique. An ideal dryer of this type would comprise a vertical, cylindrical contact zone in which the gas and the dispersed liquid droplets are uniformly, regularly distributed, with the liquid being dispersed or entrained therein in the form of substantially equally sized droplets. Ideally, all of the droplets would follow the same flow path through the apparatus as to be subjected to the same treatment and, accordingly, to continuously give rise to the formation of identical product. Stated differently, the entire volume of the physical phase to be treated, in this spray drying event the same being a dispersed liquid droplet phase, should be subjected to the same historical profile operationally in order to receive an essentially identical amount and duration of treatment by the treatment medium or phase, under the same conditions [especially those of temperature and concentration]. And the immediately aforesaid of course presupposes or implies the realization or attainment of a precisely, indeed near perfectly controlled rate of flow.
In our copending application, Ser. No. 770,802, filed Feb. 27, 1977 [a continuation of our abandoned parent application, Ser. No. 479,774, filed June 17, 1974], it has been shown that certain conditions very close to the ideal can be attained by insuring flow or distribution of vortex type, by operating within certain well defined parameters of both geometry and kinetics. As disclosed in the noted application Ser. No. 770,802 [hereby expressly incorporated by reference in its entirety and relied upon], in an initial stage in the process the plural phases are manipulated upstream of their convergence by supplying same to a cylindrical distribution zone, at least one of the phases being introduced via a helical trajectory inducing inlet and being axially extended, while maintained in an axially symmetrical, helical flow path, through said distribution zone. By "axially symmetrical, helical flow path", there is denoted a regularly repeating, helical path of axially extending downward flow which is essentially symmetrical with respect to at least one plane containing the axis of such helical flow. At least one other phase is also introduced to the distribution zone, via suitable inlet and it too is axially extended therethrough, but in this instance the path of downward flow is essentially rectilinear. The longitudinal axis of the path of rectilinear flow is, moreover, coaxial with the longitudinal axis of the path of helical flow. The current of circulating helical flow next progresses to a confining zone of restricted flow passage so constructed that the minimum momentum of the helical flow is at least 100 times greater than the momentum of the coaxial rectilinear flow, and such that the plural flow paths or separately supplied phases converge and are combined, blended and admixed in yet a third distinct zone, the contact zone. Thus, the trajectory imparted by the helical flow, at its point of exit from the zone of restricted flow passage, forms one of the classes of generatrices of a hyperboloid to a thin surface, or, more correctly, a layered stack of a plurality of hyperboloids. Said generatrices are conveyed through a series of circles to form a ring of narrow width which is situated downstream of the restricted passage for the helical flow, but upstream of its divergence. This ring surrounds a zone of depression, the effects of which are manifested both upstream, on the phase constituting rectilinear flow, as well as downstream, on the phase constituting circulating helical flow, by effecting the recycling of a portion of such fluids. In this fashion, in the zone downstream from the area of combining or convergence of the separately supplied fluids or plural flow paths, and in the same plane which is perpendicular to their coaxis all vectors of velocity of the individual elements constituting total volume are equal in absolute value, are divergent and are mutually subtracted upon rotation about the coaxis; hence, at two successive intervals, two distinct units of volume in the same trajectory evidence the same historical processing profile, thus assuring maintenance of contact between the two phases. Accordingly, if the rectilinear flow, for example, be constituted of a liquid phase and the helical flow of a gaseous phase, the liquid phase will be disintegrated, fractionated or atomized into a multitude of droplets, with each droplet being dispersed in a given volume of the gas and subjected to a certain movement or velocity thereby, by being physically swept along with said gas, thus creating the effect of centrifugation; this phenomenon enhances contact with the vector gas and, in those cases where combustion results, insures ignition and flame stability. Such a process, therefore, is a notably marked advance in the art of rapid intimate contact between two disparate phases. Nonetheless, a product separation problem arises, for example, the elimination of gases from any solid or liquid phase recovered. In our aforementioned application, Ser. No. 770,802, this function of separation is assured by means of a cyclone. Unfortunately, though, such a device has considerable space requirements and if it be necessary that a predetermined efficiency be attained, utilization of such a device fosters a substantial cost increase, even without taking into account energy loss. Modification of the cyclone itself has also been proposed to alleviate such problems, for example, by placing helical guide vanes or the like inside the cyclone. But, as can be seen from, e.g., Perry and Chilton, Chemical Engineers' Handbook, 5th Edition, pp. 20-86, McGraw-Hill Book Co., such vanes or the like, when placed inside the cyclone, will have a detrimental effect on performance of the unit because of reduced pressure throughout and a correspondingly even greater reduction in collection, or product recovery, efficiency.